Static behaviour of two-tiered Dou-Gong system reinforced by super-elastic alloy

Dou-Gong system in Asian timber structures play an important role in resisting seismic action. Traditional carpentry in Asia uses timber pegs to connect components which enables relative movement between components, and hence provide friction to dissipate energy in an earthquake. This method however has some short falls such as inadequate stiffness to resist large lateral force and therefore the structures tend to exhibit permanent deformation after the earthquakes. This study proposes a new technique by using super-elastic alloy bars to replace the conventional wooden peg connections to enhance the seismic performance of the structures. Static push-over experiments were conducted on full scaled two-tiered Dou-Gong systems and the high-strength steel and conventional wood pegs as benchmarks. The ultimate stiffness of Dou-Gong system has shown increase by using both high-strength steel and super-elastic alloy bars, but only super-elastic alloy can provide a consistent high damping ratio. This technique also involves pre-strain the super-elastic alloy and the outcomes of this series of experiments have shown that pre-strain in the super-elastic alloy can significantly increase the damping ratio in the structure and hence more energy is dissipated. The results of this paper can be used in the projects of timber structures with Dou-Gong system.